Development of the Viking Parachute Configuration by Wind-Tunnel Investigation

Several experimental investigations to obtain the drag performance of 10% scale-model disk-gap-band-type parachute assemblies trailing in the Viking forebody wake were conducted over the range of Mach 0.2 to 2.6. The wind-tunnel tests varied both the canopy trailing distance and ratio of suspension line length to canopy diameter. The data obtained permitted optimization of both parameters. Parachute drag performance in the forebody wake is markedly degraded transonically beginning at M « 0.6, reaching a minimum value at M = 1.0, then approaching the subsonic value for the selected configuration as Mach number is increased to 1.4. Further increase in Mach number causes the drag coefficient to again decline. A 20% increase in parachute-alo ne transonic drag coefficient was obtained by increasing suspension-line length ratio (S/D0) from 1.16 to 1.73. Increasing canopy trailing distance also significantly improved drag performance. Flight-test and wind-tunnel data are in good agreement.